1. Field of the Invention
The present invention relates to a display unit containing a display driver IC (integrated circuit) and an MPU controlling the display driver IC, an electronic device using the display unit, and a method of inspecting the display unit.
2. Description of the Related Art
FIG. 1 is a schematic sectional view of a display unit of a cellular phone. As shown in FIG. 1, the display unit of a cellular phone comprises a liquid crystal module 20 using a liquid crystal display driver IC 10 with an inspection circuit built therein, a printed circuit board 30 with an MPU 300 mounted thereon, and a connector 40 electrically connecting the liquid crystal module 20 and the printed circuit board 30. The connector 40 is made of an elastic connecting member (zebra rubber) having conductive parts and insulating parts alternately formed, for example. The elastic connecting member 40 is formed from conductive parts and insulating parts alternately layered in the longitudinal direction from the back side to front side of the drawing in FIG. 1. The terminals of the liquid crystal module 20 and the terminals of the printed circuit board 30 are electrically connected by evenly applying a pressure to the elastic connecting member 40 in the longitudinal direction.
The liquid crystal module 20 has a liquid crystal display section 28 having a structure in which a liquid crystal 26 is sealed between two glass substrates 22 and 24. The liquid crystal display driver IC 10 is mounted on the extended portion of the substrate 24.
Here, if the pressure applied to the elastic connecting member 40 is not even, the connection of the liquid crystal module 20 and the printed circuit board 30 becomes faulty.
Inspection of the connection has conventionally been performed by driving the liquid crystal display driver IC 10 based on a signal from the MPU 300 for displaying the display patterns on the liquid crystal display section 28 and visually inspecting the patterns.
The manufacturing process of this type of display unit has been completely automated except the above-described visual inspection process. Only the inspection process cannot be automated because it requires the visual inspection.
Moreover, because a faulty connection may be overlooked by mistake in the visual inspection, such inspection must be improved in terms of accuracy.
Furthermore, marketing strategy of electronic equipment manufacturers to satisfy recent demands of end users requires fabrication of several types of display units each having different specifications such as a display capacity, screen size, and other items. In this case, if the parts having different specifications are separately fabricated, not only an increased number of parts to be fabricated results in an increase in the cost, but also handling of the parts becomes complicated.